Since a recent backend change, a bdep has a hdrmd5 by default. That
is, osc always downloads these bdeps from the API (unless they are
cached) instead of a mirror. This is not intended.
Using a mirror is no problem because the hdrmd5s are verified in
the build module.
Note: If this causes a problem, one could also use "osc build
--download-api-only" to mimic the old behavior.